The Long Term Evolution Advanced standard, also known as LTE Advanced, LTE-Advanced or LTE-A, is a mobile communication standard adopted by the 3rd Generation Partnership Project (3GPP) as a major enhancement of the LTE standard. In an LTE-Advanced system, carrier aggregation technology is one of the key technologies that increase system/link capacity. Carrier aggregation requires that users capable of communications based on the LTE-Advanced standard transmit signals on multiple component carriers while maintaining compatibility with systems based on the LTE standard. Hereafter, the terms “user”, “user equipment” and “communication device” may be used interchangeably.
For a given LTE-Advanced user, the user initially transmission a primary component carrier (PCC) until carrier aggregation is activated, at which time the user transmits data packages on multiple component carriers including the PCC and one or more secondary component carriers (SCCs). When an LTE-Advanced user is in an idle state, the user transmits on the component carrier of the best channel condition, which is typically the PCC. The user monitors system information on the PCC before carrier aggregation is activated. For LTE-Advanced users, all of the component carriers utilized by the user are SCCs except for the PCC. The user schedules transmission of data packets on both the PCC and one or more SCCs after carrier aggregation is activated until carrier aggregation is released.
FIG. 8 shows a processing flow 800 of activation and release of carrier aggregation. Processing flow includes decision branches 802, 804, 806, and blocks 808, and 810.
At decision branch 802, a determination is made as to whether a user is an LTE user or an LTE-Advanced user. If “LTE user,” processing flow 800 proceeds to block 810; if “LTE-Advanced user,” processing flow 800 proceeds to decision branch 804.
At block 810, i.e., the user is an LTE user, the user schedules transmission of data packets on the PCC in compliance with the LTE standard.
At decision branch 804, i.e., the user is an LTE-Advanced user, a decision is made as to whether or not carrier aggregation is activated. If “no,” processing flow proceeds to block 810; if “yes,” processing flow 800 proceeds to decision branch 806.
At block 810, i.e., carrier aggregation is not activated, the user schedules on the PCC.
At decision branch 806, a determination is made as to whether carrier aggregation is activated but not released. If “no,” processing flow proceeds to block 808; if “yes,” processing flow 800 proceeds to block 810.
At block 808, i.e., carrier aggregation is not released, the user schedules on the PCC and one or more SCCs (block 808).
At block 810, i.e., the carrier aggregation is released, the user returns to scheduling on the PCC.
However, there may be times when carrier aggregation is not activated, transmission rate requirements of the LTE-Advanced user cannot be satisfied by scheduling on the PCC only. After carrier aggregation is activated, user scheduling information can be found on all the component carriers. However, this would increase channel cost.